I recently had a project that required many drawer slides. I was on a tight time constraint so I wanted to buy and use the Kreg Magnetic Drawer Slide Mounting Tools (link). Unfortunately, they seem to be discontinued. The only one I could find was on ebay for $150! So, I made my own from some scrap ply and a couple Harbor Freight magnets I had laying around. It worked beautifully and was well worth the couple hour investment.